HLASM Language Reference

DC Instruction—Length Constant
Offset Constant—Q
Use this constant to reserve storage for the offset into a storage area of an external
dummy section, or the offset to a label in a class. The offset is entered into this
space by the linker. When the offset is added to the address of an overall block of
storage set aside for external dummy sections, it addresses the applicable section.
For a description of the use of the Q-type offset constant in combination with an
external dummy section, see “External Dummy Sections” on page 57. See also
Figure 47 for details.
In the following example, to access the external dummy section named VALUE, the
value of the constant labeled A is added to the base address of the block of
storage allocated for external dummy sections.
A DC Q(VALUE)
The DXD or DSECT names referenced in the Q-type offset constant need not be
previously defined.
Figure 47. Q Offset Constants
Subfield Value Example Result
1. Duplication factor Allowed
2. Type Q
| 3. Type Extension D
| 4. Program type Allowed
5. Modifiers
Implicit length:
Q-type: 4 bytes
(length modifier
| QD-type: 8 bytes
not present)
Alignment:
Q-type: Fullword
| (Length modifier QD-type: Quadword
not present)
Q(DXDEXT)
Range for length: Q-type: 1 to 4 bytes QL2(DXDEXT)
| QD-type: 1 to 8 bytes
(no bit length)
Range for scale:
Range for exponent:
6. Nominal value
Represented by:
Enclosed by:
Exponent allowed:
Number of values
per operand:
Padding:
Truncation of
assembled value:
Not allowed
Not allowed
A DXD or DSECT
name (an
external symbol)
Parentheses
No
Multiple
None
Not applicable
DC Q(DUMMYEXT)
DC Q(DXDEXT)
Chapter 5. Assembler Instruction Statements 159